What's the oldest powder you have used that still produces/produced adequate to great results? I think powders can last an extremely long time with proper storage methods. The oldest powder I've personally used...and still have a few pounds left, is H4831 that was WWll surplus sold by Hodgon. It came in a cardboard keg and was 18lbs if I remember correctly. We used it in our 22-250 (with a drop tube) for varmit shooting with great results.